# Lake Malawi TEX86 Surface Temperature Reconstruction #----------------------------------------------------------------------- # World Data Service for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program # National Centers for Environmental Information (NCEI) #----------------------------------------------------------------------- # Template Version 4.0 # Encoding: UTF-8 # NOTE: Please cite original publication, NOAA Landing Page URL, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, study title, NOAA Landing Page URL, and date accessed. # # Description/Documentation lines begin with # # Data lines have no # # # NOAA_Landing_Page: https://www.ncei.noaa.gov/access/paleo-search/study/5446 # Landing_Page_Description: NOAA Landing Page of this file's parent study, which includes all study metadata. # # Study_Level_JSON_Metadata: https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/json/noaa-lake-5446.json # Study_Level_JSON_Description: JSON metadata of this data file's parent study, which includes all study metadata. # # Data_Type: Paleolimnology # # Dataset_DOI: 10.25921/j5j1-yh32 # # Science_Keywords: PAGES 2k Network, Air Temperature Reconstruction, PAGES Africa 2k #-------------------- # Resource_Links # # Data_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/malawi2005-noaa.txt # Data_Download_Description: NOAA Template File; TEX86 Data and Temperature Reconstruction # #-------------------- # Contribution_Date # Date: 2005-04-01 #-------------------- # File_Last_Modified_Date # Date: 2024-09-09 #-------------------- # Title # Study_Name: Lake Malawi TEX86 Surface Temperature Reconstruction #-------------------- # Investigators # Investigators: Powers, L.A.(https://orcid.org/0000-0001-6743-0820); Johnson, T.C.(https://orcid.org/0000-0003-4630-6788); Werne, J.P.(https://orcid.org/0000-0002-7019-6024); Castañeda, I.S.(https://orcid.org/0000-0002-2524-9326); Hopmans, E.C.(https://orcid.org/0000-0002-8209-1334); Sinninghe Damsté, J.S.(https://orcid.org/0000-0002-8683-1854); Schouten, S.(https://orcid.org/0000-0001-9200-8269) #-------------------- # Description_Notes_and_Keywords # Description: The dataset is a paleotemperature reconstruction of mean annual surface temperature from the north basin of Lake Malawi, East Africa using the TEX86 paleothermometer. (TetraEther indeX of tetraethers with 86 carbon atoms). The age model for these cores is already available for previous Lake Malawi MP98 data sets on this website. TEX86 values are means of replicate analyses. All samples were measured at least in duplicate, half of samples were measured at least in triplicate. The calibration equation used to calculate mean annual lake surface temperatures (LST) is LST=(TEX86-0.25)/0.017 with a calibration error of +/- 2 degrees C. Lake Malawi core M98-1P: 10º15.9'S, 34º19.1'E, water depth 403m. Lake Malawi core M98-2P: 9º58.6'S, 34º13.8'E, water depth 363m. Lake surface elevation 474m. #-------------------- # Publication # Authors: Powers, L.A., T.C. Johnson, J.P. Werne, I.S. Castañeda, E.C. Hopmans, J.S. Sinninghe Damsté, and S. Schouten # Published_Date_or_Year: 2005-04-01 # Published_Title: Large temperature variability in the southern African tropics since the Last Glacial Maximum # Journal_Name: Geophysical Research Letters # Volume: 32 # Edition: # Issue: 8 # Pages: # Report_Number: L08706 # DOI: 10.1029/2004GL022014 # Online_Resource: # Full_Citation: # Abstract: The role of the tropics in global climate change is actively debated, particularly in regard to the timing and magnitude of thermal and hydrological response. Continuous, high-resolution temperature records through the Last Glacial Maximum (LGM) from tropical oceans have provided much insight but surface temperature reconstructions do not exist from tropical continental environments. Here we used the TEX86 paleotemperature proxy to reconstruct mean annual lake surface temperatures through the Last Glacial Maximum (LGM) in Lake Malawi, East Africa (9º-14ºS). We find a ~3.5ºC overall warming since the LGM, with temperature reversals of ~ 2ºC during the Younger Dryas (12.5 ka BP) and at 8.2 ka BP. Maximum Holocene temperatures of ~29ºC were found at 5 ka BP, a period preceding severe drought in Africa. These results suggest a substantial thermal response of southeastern tropical Africa to deglaciation and to varying conditions during the Holocene. #-------------------- # Funding_Agency # Funding_Agency_Name: US National Science Foundation # Grant: ATM-9709291 and ATM-0081776 #-------------------- # Funding_Agency # Funding_Agency_Name: European Association of Organic Geochemists # Grant: Travel scholarship #-------------------- # Site_Information # Site_Name: Lake Malawi, cores M98-1P and M98-2P # Location: Malawi # Northernmost_Latitude: -9.9767 # Southernmost_Latitude: -10.2650 # Easternmost_Longitude: 34.3183 # Westernmost_Longitude: 34.2300 # Elevation_m: #-------------------- # Data_Collection # Collection_Name: Powers2005 M98-1P-2P # First_Year: 23880 # Last_Year: 250 # Time_Unit: cal yr BP # Core_Length_m: # Parameter_Keywords: reconstruction # Notes: #-------------------- # Chronology_Information # Chronology: Radiocarbon # Chronology_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/templates/noaa-wds-paleo-14c-terms.csv # Chronology_Download_Description: Radiocarbon terms and definitions. # Chronology_Notes: Radiocarbon dates from core M98-1P and M98-2P. Dates beginning with "AA" were determined at the University of Arizona and dates beginning with "NOSAMS" were determined at the Woods Hole Oceanographic Institution. Bulk organic carbon was dated in some samples; in others, pollen extracts (the organic residue from standard pollen preparation procedures) were dated. There was no substantial difference between dates of these different components when compared on replicate samples. Core top ages are based on correlations with multi-cores from the same site that were dated by a combination of Pb-210 stratigraphy and varve counting (Johnson et al., 2001), coupled with stratigraphic correlations of key horizons observed in the tops of the multi-cores, piston cores, and their associated pilot cores. # Rejection_Rationale: # Reservoir_Method: Subtracted 450 years from each radiocarbon date to account for reworked carbon. The 450 year "old carbon" effect was determined from dates of surface sediment from two multi-cores in the north basin, and confirmed by dates at the bottoms of the two multi-cores that were independently dated by varve counts. # Calibration_Method: CALIB 4.3 # Age_Model_Method: The calendar year ages in both cores were modified slightly to insure that key identifiable horizons such as ash layers were assigned the same age. These key marker horizons are identified in the chronology table in the notes field. # Missing_Values: # Chronology_Table: # core_id lab_code depth_cm age_14C_BP1950 age_14C_1s_yr res_age_yr age_calib_BP1950 calib_curve notes # M98-1P NaN 40.5 R1 # M98-1P AA32943 55 1880 55 450 1358 IntCal # M98-1P AA32944 166 4015 60 450 3888 IntCal # M98-1P NaN 192 O2 # M98-1P NaN 240.5 G # M98-1P AA32945 306.5 6270 65 450 6700 IntCal # M98-1P NaN 408.5 Y3 # M98-1P NaN 459.5 d # M98-1P AA32946 460.5 9010 85 450 9582 IntCal # M98-1P NaN 473 D # M98-1P NaN 509 E # M98-1P NaN 565 F # M98-1P NaN 606.25 O3 # M98-1P AA32947 627.5 13330 100 450 15561 IntCal # M98-1P NaN 643.5 I # M98-1P NaN 703.5 B # M98-1P NaN 751.5 b # M98-1P NaN 757.5 A # M98-1P AA32948 765.5 19010 270 450 22086 IntCal a # M98-2P NaN 60.5 R1 # M98-2P NOSAMS 20475 139.5 2510 50 450 2048 IntCal # M98-2P NOSAMS 20476 248.5 4020 65 450 3893 IntCal # M98-2P NaN 272.5 O2 # M98-2P NaN 325.25 G # M98-2P NOSAMS 20477 379 6260 65 450 6688 IntCal # M98-2P NaN 488.5 Y3 # M98-2P NOSAMS 20480 500.5 8820 110 450 9477 IntCal # M98-2P NOSAMS 20478 537.5 9550 120 450 10248 IntCal d # M98-2P NaN 550.63 D # M98-2P NaN 592 E # M98-2P NOSAMS 19968 648.5 11450 100 450 13048 IntCal # M98-2P NaN 650.25 F # M98-2P NaN 697.75 O3 # M98-2P NaN 737 I # M98-2P NOSAMS 20485 744 15150 130 450 17644 IntCal # M98-2P NaN 779 B # M98-2P NaN 828 b # M98-2P NaN 834 A # M98-2P NaN 844 a # M98-2P NOSAMS 20481 900 21000 240 450 24333 IntCal #-------------------- # Variables # # PaST_Thesaurus_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/PaST-thesaurus/SKOS/past-thesaurus-v1.0.rdf # PaST_Thesaurus_Download_Description: Paleoenvironmental Standard Terms (PaST) Thesaurus terms, definitions, and relationships in SKOS format. # # Data variables follow that are preceded by "##" in columns one and two. # Variables list, one per line, shortname-tab-var components: what, material, error, units, seasonality, data type, detail, method, C or N for Character or Numeric data) # ## CoreID sample identification,,,,,paleolimnology,,,C,core name ## Age age,,,calendar kiloyear before present,,paleolimnology;climate reconstructions,,,N, ## TEX86 tetraether index of 86 carbon atoms,,,dimensionless,,paleolimnology,averaged,,N, ## Temp lake surface temperature,glycerol dialkyl glycerol tetraether index,,degree Celsius,annual,paleolimnology;climate reconstructions,,,N,TEX86 ## SD lake surface temperature,glycerol dialkyl glycerol tetraether index,one standard deviation,degree Celsius,annual,paleolimnology;climate reconstructions,,,N,TEX86 #-------------------- # Data: # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing_Values: CoreID Age TEX86 Temp SD M98-1P 0.25 0.69 25.88 0.86 M98-1P 0.57 0.69 26.17 0.19 M98-1P 1.75 0.71 26.87 0.76 M98-1P 2.96 0.69 26.16 0.71 M98-1P 3.32 0.7 26.6 0.21 M98-1P 3.54 0.7 26.71 0.43 M98-1P 4.23 0.72 27.79 0.45 M98-1P 4.45 0.72 27.49 0.56 M98-1P 4.77 0.73 28.52 0.46 M98-1P 5.05 0.74 28.93 0.58 M98-1P 5.46 0.74 28.61 0.02 M98-1P 6.22 0.72 27.6 0.11 M98-1P 6.72 0.72 27.58 0.22 M98-1P 7.45 0.68 25.06 0.78 M98-1P 7.58 0.69 25.91 0.56 M98-1P 7.79 0.68 25.09 0.25 M98-1P 8.02 0.69 25.81 0.02 M98-1P 8.23 0.66 24.35 0.23 M98-1P 8.92 0.69 26.17 0.67 M98-1P 10.23 0.69 25.85 0.71 M98-1P 10.9 0.68 25.52 0.49 M98-1P 11.46 0.7 26.44 0.78 M98-1P 11.94 0.7 26.6 0.64 M98-1P 12.2 0.69 25.84 0.12 M98-1P 12.51 0.68 25.3 0.14 M98-1P 12.72 0.68 25.48 0.55 M98-1P 12.98 0.71 27.13 0.28 M98-1P 13.52 0.69 25.64 0.18 M98-1P 13.74 0.72 27.49 0.08 M98-1P 13.84 0.73 28.15 0.55 M98-1P 14.29 0.71 27 0.06 M98-1P 14.51 0.7 26.37 0.65 M98-1P 14.89 0.69 25.86 0.66 M98-1P 15.94 0.67 24.97 0.57 M98-1P 17.58 0.65 23.48 0.77 M98-1P 18.52 0.64 23.09 0.83 M98-1P 19.01 0.64 23.13 0.74 M98-1P 20.01 0.63 22.58 0.58 M98-1P 20.78 0.63 22.52 0.43 M98-1P 21.77 0.66 23.98 0.3 M98-2P 22.43 0.66 24.13 0.01 M98-2P 23.24 0.67 24.48 0.58 M98-2P 23.88 0.66 24.19 0.03